$bc + 10bd - 7b + 1 = 10c - 6$ Solve for $b$.
Answer: Combine constant terms on the right. $bc + 10bd - 7b + {1} = 10c - {6}$ $bc + 10bd - 7b = 10c - {7}$ Notice that all the terms on the left-hand side of the equation have $b$ in them. $1{b}c + 10{b}d - 7{b} = 10c - 7$ Factor out the $b$ ${b} \cdot \left( c + 10d - 7 \right) = 10c - 7$ Isolate the $b$ $b \cdot \left( {c + 10d - 7} \right) = 10c - 7$ $b = \dfrac{ 10c - 7 }{ {c + 10d - 7} }$